The present invention relates to apparatus for, and a method of, driving a tunnel, adit, gallery or similar excavation referred to throughout this specification and claims as a tunnel.
It is known to drive a tunnel with the aid of a forward cutting cylinder shield device and to produce a lining for the tunnel by introducing fluid concrete into a space formed behind the shield device. It is important to produce the concrete lining as quickly as possible to avoid settlement of the surrounding material and to preclude breakage or caving in of the tunnel wall. Nevertheless, the setting time of the concrete usually means that the tunnel driving cannot proceed at the optimum speed of advancement of the device effecting the tunnel driving. To reduce the concrete setting time, it is known, for example from U.S. Pat. No. 3,834,170, assigned to the assignee of this application, to withdraw water from the fluid concrete via filter plates thrust against the concrete by fluid rams serving to advance the device. It is also known to enhance this effect by creating a suction on the filters. One major disadvantage of the prior art is that although the driving and concreting operations can be carried out independently the compression of the fluid concrete, usually occurs when the shield device is advancing and needs a stable firm abutment. Where the concrete still contains a lot of water adequate retainment and support of the concrete with strong formwork is necessary.
Where the so-called knife or drive shields are used which employ a series of elongate cutter planks carried by a frame, rams are coupled between the frame and the planks and enable the shield to be advanced as a unit without requiring any additional support by the tunnel lining even indirectly. However, in this case, special additional measures such as temporary linings, are usually adopted to support the critical tunnel wall zone between the rear of the shield and the permanent lining.
A general object of this invention is to provide an improved apparatus for and method of tunnel driving.